In general, the present invention relates to a door winding device. Such devices are commonly used to maintain and adjust the tension of a spring used to counterbalance the weight of a door. A door may be an upwardly acting door, such as, for example, a rolling door having a curtain made of flexible material which is coiled about a drum wheel or a sectional door made up of a plurality of panels. To provide a counterbalancing force for the weight of the door, a spring is attached at one end to one or more of the drum wheels and at its other end to a tensioning assembly. In the past, the door's support bracket would act as the tensioning assembly.
Sectional doors retain many of the same components as the described rolling door, but differ slightly in operation. In particular, as opposed to rolling the door about drum wheels mounted on the axle, most sectional doors employ a track system that guides the door panels from a generally closed vertical position to a generally open horizontal position. As in the case of a rolling door, the sectional door employs a counterbalance system having a spring to counteract the weight of the door. In both sectional and rolling doors, once the door and axle were mounted on support brackets, the free end of the spring would be attached to one support bracket and the spring would be rotated to charge the spring. Optimally, the counterbalance spring would have sufficient tension, such that the door would fully close and only a small amount of force would be necessary to raise the door from the closed position. If the door is not in the optimal position, the installer would adjust the spring tension by repositioning the end of the spring and the support bracket. After which, the installer would reassemble these components and repeat the pre-tensioning procedure to charge the spring.
To avoid repositioning of the spring on the bracket, alternative tensioning assemblies have been developed. In one such assembly, an axle tube is provided with a spring attaching plate and a tensioning plate. The tube is fit over the axle such that the plates may move independently of the axle. The plates are located on either side of the tensioning bracket and an end of the counterbalance spring passes through the spring attaching plate to eventually attach to the bracket. With the spring so attached, the axle tube may be rotated to increase or decrease tension on the spring. The plates are provided with multiple holes located radially equidistant from the center of the axle. To maintain the tension on the spring, a pin is passed through the holes in each plate to fix the plates relative to each other and the bracket preventing rotation of the axle tube. Adjustment may be made by removing the pin and rotating the axle tube hole to the next appropriate hole and reinserting the pin.
As will be appreciated, this tensioning assembly may be difficult to use. The user must rotate the axle tube with a suitable tool in one hand to align the holes in the spring attaching plate, tensioning bracket, and tension plate, and, with the other hand, attempt to insert a pin through these holes. As a result, once the installer has the holes aligned, he must maintain the exact tension on the axle tube to preclude relative rotation that would take the holes out of alignment.
A further disadvantage of this system is that the slidable pin may become disengaged by efforts to tamper with the door or other accidental contact with the pin. Essentially, the pin is not axially held, but for the frictional forces created by the plates and bracket. Therefore, a person could remove the pin without tools or extensive effort causing unintentional release of the spring's tension. It will be appreciated that such a release could make it difficult or impossible to operate the door and, in more dire instances, cause serious injury.
In another system, a collar is slipped over a rod around which the counterbalance spring is wound. The collar engages the spring and is fitted with a pair of ratcheting mechanisms and a assembly to hold the same in place while the ratchets are used to apply the correct tension to the spring. A similar system provides a tool for applying rotational force to a coiled torsion spring of a door counterbalancing mechanism including a split housing fixedly mounted onto a winding cone of the torsion spring. The housing has a sprocket provided with annular grooves on either side. A right-hand operated ratchet tool and left-hand ratchet tool fit within the corresponding grooves and are used sequentially in unison to create stored energy within the torsion spring. Still another tool includes an adapter used with existing door structures to tension the springs during periodic maintenance. The adapter includes a body that may be mounted upon a rotatable shaft supporting the coil springs and is nonrotatably attached to the end of the coil spring and rotatable shaft. The system further includes two improved wrenches for tensioning the springs, which have jaws that engage splines on the adapter body. To tension the door, the splines are engaged and rotated with the wrenches in an alternate manner, such that the coil spring is wound to increase or decrease the tension stored therein. It will be appreciated that the above-described systems are impractical to ship with each door and may be difficult for an inexperienced installer to use, if not dangerous.
Still other systems of tensioning a door in the industry employ a worm gear/worm reducer that allows the use of an electric power tool, such as a drill motor, to tension the door's counterbalance springs. These systems are generally made integral with the counterbalance system and significantly increase the overall cost of the door. Since a power tool is required to tension the door, it will be appreciated that, when the door is installed before the home or other structure is complete and before electric power is available, it may be impracticable or impossible to fully install the door. In addition, theses systems typically require a wind counter to indicate the tension on the door spring, which may not be easily viewed in the sometimes dark conditions in a garage without electrical power.